This invention relates generally to telescopic spectacles and more particularly to surgical telescopic spectacles.
As is known in the art, telescopic spectacles are used by surgeons and others who require a clear magnified view of their work area. Typically the telescopes are arranged either in pairs with one telescope positioned for viewing by each eye of the wearer or alternatively, with a single telescope with optics to permit viewing through the single telescope from each eye.
It is difficult for human eyes to observe a small object located beyond a small opening or in or at the end of a narrow passageway. When the object is brought close enough to see clearly, there may be problems with stereoscopic focusing through the opening or along the narrow passageway using both eyes. Use of one eye to obtain a satisfactory focus has the disadvantage of loss of depth perception. When the object is sufficiently spaced from the eyes to the provide a satisfactory stereoscopic focus, visual acuity is diminished. Thus, stereoscopic focus and visual acuity are competing factors.
Furthermore, when it is necessary or desirable to illuminate the object being viewed by projecting illumination through the opening or narrow passageway, additional problems are presented.
This is particularly true in the surgical field where the surgeon must position himself sufficiently distant from the operating area to enable him to operate while being sufficiently close thereto to enable him to clearly see the operating area. This distance may place the surgeon's eyes in the range of from about 8 inches to about 30 inches from the operating area. In these ranges the aforementioned problems of visual acuity and stereoscopic focus exist particularly for small objects.
One approach for solving this problem is to use an operating room microscope. One problem with this approach, however, is that such microscopes are large and bulky and burdensome to move, use and adjust. Furthermore, such microscopes restrict the surgeon's mobility and may cause eye fatigue during long periods of use. A further problem is that it is difficult with such microscopes to project illumination through small openings or long narrow passageways through the operating area and at the same time view the area.
Another approach to solving this problem is to use individual surgical telemicroscopes and eye loops on a headband worn by the surgeon. This approach, however, is not entirely satisfactory in that it is still difficult to obtain stereoscopic vision and depth perception particularly through small openings in or at the end of narrow passageways.
Moreover, in the telemicroscope approach, a problem exists in trying to align the telescopic lenses with the eye of the user. This problem leads to degradation of peripheral vision, distortion caused by the magnification, loss of depth of field, reduction of field of view, and reduction in visual acuity and clarity. These problems are accentuated when the user has a vision defect such as myopia or hyperopia which must be corrected with the aid of prescription spectacles. That is, the above mentioned problems are accentuated when the user wears a prescription lens to correct a vision defect since the telescope must often be placed on an outer surface of the prescription lens relatively far from the user's eye. Furthermore, the weight of such optics is burdensome to surgeons during long surgical procedures.